this is a bad idea because much like the one fc incident with sylvia and arvloski it will lead to confusion and DQ's, they should just make it completely legal to avoid that mess

They definitely should have clear rules in this aspect of the game. There are situations where you can give the referees more subjective competence (i.e. stalling, where the referee has also enough time to warn the fighter), but in this case with the kicks and knees to the head, it's something that can affect the outcome of the fight in a split second. Because of the non clear situation in the Sylvia vs Arlovski incident One FC changed the rules to clearly allow those kicks.

Just make it so if any part of your body that isn't your feet or hands is on the ground you are grounded. It is that simple you don't need to give refs some ridiculous judgement call or base it on how many points of the body are down.